Re:Num7
Challenges your working memory
Free
How about a brain training game during your spare moments?
It's very simple, yet gradually gets harder.
Experience this wonder for yourself.
Have fun!
“Re:Num7” Welcome to the app!
This app challenges your working memory.
[Magic Number 7±2]
It is believed that we use temporary memory, or “working memory,” to remember information like numbers temporarily—especially when they have no particular meaning in sequence—such as when dialing a phone number from a handwritten note.
Cognitive psychology suggests that, while individual differences exist, most people can handle chunks of information—essentially blocks of data—with a capacity of around 7, or 7±2 items.
This is known as the “Magic Number 7±2.”
This app will help you test the capacity of your working memory.
See for yourself if this magic number holds true for you—whether your capacity is larger or smaller.
Purpose:
Present a number with a specified number of digits, hide it, then have the user recall and input the number. If it matches, it's OK. Perform 10 sets of this task and observe the accuracy rate. A perfect game is achieved with all questions correct.
Calculate a score based on the number of digits and accuracy rate, and compete with others. Scores can be recorded with a nickname and displayed in a ranking.
This is expected to provide the following benefits:
・Gain an estimate of your working memory capacity
・Repeated practice may increase working memory capacity
・Similarly, it may help prevent or slow cognitive decline associated with aging
・Improves concentration, and above all, getting answers right is fun
Features:
・Choose your preferred keypad layout for number input: phone layout, calculator layout, or (on iPad) horizontal row layout
・You can select the number of digits, generation method, and display method
Digit Count:
Each level offers three consecutive digit counts, plus a mode where these three counts are increased in three stages from shortest to longest
Generation Method:
Choose between a method that minimizes repetition (like drawing cards from a deck) or a completely random method
Display Method:
Options include showing all digits at once or displaying digits sequentially (step-up). A non-hidden method is also available, but the score will be 0
・It is divided into four levels based on the range of digit counts.
Beginner:
Choose 5, 6, or 7 digits, or step-up from 5 to 7 digits. Most players should be able to clear this.
Intermediate:
Choose 7, 8, or 9 digits, or step-up from 7 to 9 digits. Clearable with effort.
Advanced:
9, 10, 11 digits. You can choose step-up from 9 to 11 digits. With effort, some may be clearable.
Extra:
11, 12, 13 digits. You can choose step-up from 11 to 13 digits. This likely exceeds human capability.
Therefore, it is not locked. Aim to clear even a part of it with effort.
・A tutorial function is provided to make getting started easier.
・While primarily designed for individual play, you can register scores with a custom nickname upon game completion, allowing friendly competition with family or friends.
・(NEW) We've prepared a mode that's easier to play, though your score will decrease.
- Doubles the display time for challenge numbers (score halved)
- Displays the C (Clear entry) key to re-enter input (using it reduces that challenge's score by 10%)
The challenges themselves are simple and straightforward. However, actually attempting them reveals how difficulty skyrockets with increasing digit counts, offering a fascinating experience.
Ratings & Reviews
This app hasn’t received enough ratings or reviews to display an overview.
We've prepared a mode that's easier to play, though your score will decrease.
・Doubles the display time for challenge numbers (score halved)
・Displays the C (Clear entry) key to re-enter input (using it reduces that challenge's score by 10%)
The external libraries used have been upgraded.
The developer, 有限会社知識情報研究所, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Katsuhiro Kamada
- Size
- 9 MB
- Category
- Education
- Compatibility
Requires iOS 17.6 or later.
- iPhone
Requires iOS 17.6 or later. - iPad
Requires iPadOS 17.6 or later.
- Languages
- English and Japanese
- Age Rating
13+
- 13+
- Copyright
- © 2025, 2026 有限会社知識情報研究所